A Simplified CCEP Analysis Pipeline Reveals Correlation with Spike Propagation Networks in Pediatric Patients with Refractory Focal Epilepsy
Abstract number :
2.164
Submission category :
3. Neurophysiology / 3E. Brain Stimulation
Year :
2024
Submission ID :
426
Source :
www.aesnet.org
Presentation date :
12/8/2024 12:00:00 AM
Published date :
Authors :
Presenting Author: Patrick Davis, MD PhD – Children's Hospital of Philadelphia
Krzysztof Sadowski, MD PhD – Boston Children’s Hospital, Harvard Medical School
Michelle Chiu, MD – Boston Children's Hospital
Jurriaan Peters, MD PhD – Boston Children’s Hospital, Harvard Medical School
Rationale: Accurate identification of seizure initiation and propagation networks remains a central challenge. Analysis of cortico-cortico evoked potentials (CCEPs) is a powerful tool to interrogate the structure of epileptic networks, and may facilitate improved epilepsy surgical outcomes by assisting in identification of the Epileptogenic Zone (EZ). However, investigations employing CCEPs are uncommon in pediatric cohorts, which may be due to the perceived availability of relevant datasets or high barrier to entry. Furthermore, how CCEPs relate to other measures of connectivity in pediatric patients is largely unknown. This project applies a simplified CCEP analysis pipeline to investigate whether this technique can assist in identification of EZ in pediatric patients with refractory focal epilepsy.
Methods: We retrospectively analyzed stereo-EEG and clinical data from a small cohort (n=8) of patients with refractory focal epilepsy for whom low-frequency stimulation (1Hz) was performed as part of their surgical evaluation, and developed a streamlined data analysis pipeline to extract CCEPs using the MATLAB-based software package Brainstorm. In parallel, we calculated other metrics of network connectivity such as Granger Causality (GC) and interictal spike propagation. Using a simplified analytic process, we compared these metrics in combination across EZ, Irritative Zone (IZ), and normal tissue.
Results: We were able to extract high-quality CCEP responses from this clinical dataset. CCEP amplitudes broadly followed the trajectory of spread through the seizure network, and early responses inversely correlated with distance from the stimulation site (Spearman R = -0.5 – -0.6). We found only weak correlation with Granger Causality (R = 0 – 0.4), suggesting these metrics interrogate distinct aspects of network structure. In patients with post-operative seizure freedom, propagation of stimulus-induced discharges (CCEPs) from the EZ, but not adjacent IZ, was highly correlated (R = 0.5 – 0.8) with propagation of spontaneous interictal discharges.
Conclusions: This small pilot study describes a simple analytical pipeline to expand the use of CCEPs into additional pediatric populations, and report a novel relationship between stimulus-induced (CCEP) and spontaneous (interictal) spike propagation through epileptic networks. Preliminary evidence suggests that this combined CCEP network analysis may be useful to delineate EZ from IZ in pediatric surgical epilepsy patients.
Funding: n/a
Neurophysiology